Topic: Equations

Objectives: To solve linear equations with the unknown on one side or two sides.

(Level 5/6)

Keywords: equation, unknown, operation, inverse, balance, solve

Monday 10 April 2023

Mental Algebra StarterYou have 10 seconds for

each question (1 – 10)

1

3a +5a

2

3b + 2 + 2b + 4

25y – 11y

3

17c + 2c – 5c

4

If d = 3, what is 4d?

5

If e = -3, what is 2e?

6

If t = 2, what is 4(t+1)?

7

If x = 5, what is 4(x-1)?

8

If d = 3, evaluate 5d+1

9

2y=6

What is y?

10

Answers

1) 8a 6) -6

2) 5b + 6 7) 12

3) 14y 8) 16

4) 14c 9) 16

5) 12 10) 3

Great job!

If I add 7 to a number I get 18.What is my number?

My number is 11

Together 2 bags of sweets contain 40 sweets.How many sweets in each bag?

Each bag contains 20 sweets

Ali will be 21 years old, in 8 years time.How old is Ali?

Ali is 13 years old

Great job!

Equations – Success if you can do these

3x = 6

x/4 = 2

x + 3 = 17

x – 4 = 13

3x + 4 = 25

4x – 3 = 17

© T Madas

n + 5 = 12

n+5

12

12–57

n = 7

If I add 7 to a number I get 18.What is my number?

n = 18

n+7

1818

–711

n = 11My number is 11

+ 7

Together 2 bags of sweets contain 40 sweets.How many sweets in each bag?

2b = 40

bx2

4040

÷220

b = 20Each bag contains 20 sweets

Ali will be 21 years old, in 8 years time.How old is Ali?

a = 21

a+8

2121

– 813

a = 13Ali is 13 years old

+ 8Age now

How to solve thex + 3 = 10

type of equation

You get rid of the

+ 3 by - 3

But you must subtract 3 from both

sides

x + 3 =10

x + 3 – 3 = 10 - 3

x = 7

For equations like x + 3 = 10

just subtract 3 from both sides

x + 3 = 10

x = 10 - 3

x = 7 Like this

How to solve thex – 3 = 7

type of equation

You get rid of the

– 3 by

+ 3

But you must to add 3 to both sides

x – 3 = 7

x – 3 + 3 = 7 + 3

x = 10

For equations like x – 3 = 7

just add 3 to both sides

x – 3 = 7

x – 3 + 3 = 7 + 3

x =10 Like this

How to solve the5x = 20

type of equation

5x = 20 means 5 X x =

20

5x = 20

5 X x = 20

5x = 20 means 5 X x =

20

So, you get rid of the 5 X by

÷ 5

5x = 20

5 X x ÷ 5 = 20 ÷ 5

5x = 20 means 5 X x =

20

So, you get rid of the 5 X by

÷ 5

5x = 20

5 X x ÷ 5 = 20 ÷ 5

x = 4

5x = 20 means 5 X x =

20

So, you get rid of the 5 X by

÷ 5

But you must divide both sides by 5

5x = 20

5 X x ÷ 5 = 20 ÷ 5

x = 4

For equations like 5x = 20

just divide both sides by the number that multiplies the x.

5x = 20

x = 20 ÷ 5

x = 4 Like this

How to solve thex/3 = 4

type of equation

x/3 = 4

x ÷ 3 = 4

It means

x ÷ 3 = 4

x/3 = 4

x ÷ 3 = 4

x ÷ 3 X 3 = 4 X 3

Get rid of

÷ 3 by

using a

X 3

It means

x ÷ 3 = 4

x/3 = 4

x ÷ 3 = 4

x ÷ 3 X 3 = 4 X 3

x = 12

Get rid of

÷ 3 by

using a

X 3

It means

x ÷ 3 = 4

x/3 = 4

x ÷ 3 = 4

x ÷ 3 X 3 = 4 X 3

x = 12

Get rid of

÷ 3 by

using a

X 3

You must

X 3 on both

sides

It means

x ÷ 3 = 4

For equations like x/3 = 4

just multiply both sides by the number that divides the x.

x/3 = 4

x = 4 X 3

x =12 Like this

                              Remember, always do the same thing to both sides.

Felix is checking that you do this properly.

x/3 = 12

x ÷ 3 X 3 = 12 X 3

x =36

If I double my house number and then subtract 4, I get 18.What is my house number?

2n = 18– 4

nx2 18

18+411

– 4

22÷2

n = 11I live at number 11

Cassie has 5 stamps. She bought another three books of stamps and now has 23 stamps.How many stamps in each book?

5 = 23+ 3b3b + 5 = 23

bx3 23

23–56

+5

18÷3

b = 6Each book contains 6 stamps

Plenary: Evaluating your own progress

Now go over your work, taking note of the mistakes and errors that you made. • At what Level would you assess yourself ?

• Describe something that you have learned.

• Do you feel you have met the objectives of the lesson?

• Write one sentence to describe your progress in this lesson.

Great job!